In a plate cooler of the type defined above, it is already known to make a bypass flow in the cold state possible, by providing bypass channels, parallel to the fluid channels, in the package between the distributor box and the collection box, and in the vicinity of the bypass channels, the distributor box provided on the fluid inflow side is equipped in the vicinity of the bypass channels with a valve, which enables the communication between the distributor box and the bypass channels in the cold state.
In a hydraulic oil air cooler, it is also known for the hydraulic oil lines, leaving the distributor box and discharging into the collection box, to be formed by platelike extruded profiles of hollow cross section.
A further known embodiment comprises providing the extruded profiles with integrally formed-on inner ribs. In this way, the cooling surface area for the hydraulic oil is enlarged, and thus the cooling power is increased. For the same reasons, it is especially advantageous if the extruded profiles have a multiple-compartment cross section.
In the known construction, the platelike extruded profiles are soldered on the ends into openings in the distributor box and in the collection box, which while it is an economical manufacturing method still necessitates soldering in a vacuum or in an inert gas (CAB), which is relatively expensive.